Co‐expression of different types of Fc receptors on murine peritoneal macrophages

Abstract

Simultaneous expression of particular immunoglobulin Fc receptors (FcR) was studied on the plasma membranes of murine peritoneal macrophages. This was facilitated by the use of sheep red blood cells (SRBC) and/or synthetic microspheres coated with monoclonal antibodies of different isotypes. It was concluded that a majority of macrophages bear more than one type of FcR; macrophages bearing at least three types of FcR were present in the peritoneal cavity; macrophages bearing FcμR did not bind IgE, IgA or IgG; all macrophages bearing FcαR also expressed Fcγ_2bR, Fcγ₃R, and FcεR; all macrophages bearing FcεR also expressed Fcγ_2bR and FcαR. Except for FcαR, essentially equivalent numbers of FcR‐bearing macrophages were detected when antibody‐coated SRBC or polymeric microspheres were used. Simultaneous applications of these reagents permitted the most detailed and direct investigations yet performed of multiple FcR expression on individual cells.